1. Field of the Invention
The present invention relates to a barrier film having the extremely high barrier property which is used as a wrapping material for foods, medical products and the like, a packaging material for electronic devices and the like, or a substrate material, a method for manufacturing the same, and a laminated material, a container for wrapping and an image displaying medium using this barrier film.
2. Description of the Related Art
Conventionally, as a wrapping material having the barrier property to an oxygen gas and water vapor, and the better storage suitability for foods, medical products and the like, various materials have been developed and proposed, such as a barrier film having a composition in which a coating layer of polyvinylidene chloride or an ethylene vinyl alcohol copolymer is provided on a flexible plastic substrate.
However, in these barrier films, there is a problem that the barrier property to oxygen and water vapor is not sufficient, and the barrier property is remarkably reduced, in particular, at sterilization treatment at a high temperature. Further, a barrier film with a coating layer of polyvinylidene chloride provided thereon generates harmful dioxin at burning, and adverse effect on the environment is concerned.
Therefore, recently, a barrier film having a composition of an inorganic oxide deposition film such as silicon oxide, aluminium oxide and the like is provided on a substrate film, has been proposed. In addition, lamination, of a resin layer comprising an epoxy resin or a mixture thereof with the above-mentioned deposition film, is proposed (JP-A 8-164595).
On the other hand, in an electronic device, for example, in an image displaying device such as flexible display, when a barrier film is used as a substrate for a plastic film base which is a substitute for a glass substrate, or when a barrier film is used as a cover film for a solar cell module, the higher barrier property as compared with the barrier property required in utility of the conventional wrapping (e.g. an oxygen transmission rate is 1.0 cc/m2/day•atm or smaller, a water vapor transmission rate is 11.0 g/m2/day or smaller) is required to a barrier film. In addition, the heat resistance and the chemical resistance such as resistance to a high temperature at preparation of a display element and various treating chemicals are required to a barrier film and, further, also after the barrier film is made into products, it is required to maintain a high barrier property under the severe environment such as a resistance to wet heat test.
The conventional barrier film with an inorganic oxide deposition film such as silicon oxide, aluminium oxide and the like provided thereon is excellent in the transparency, and has little influence on the environment, and an its demand for a wrapping material and the like is greatly expected. However, the barrier property of these barrier films is still lower as compared with a laminated material for wrapping using an aluminium foil, and there is a problem in serviceability in use in an electronic device requiring the particularly high barrier property (e.g. an oxygen transmission rate is 0.1 cc/m2/day•atm or smaller, a water vapor transmission rate is 0.1 g/m2/day or smaller).